Eight human volunteers were immunized with S. mutans strain OMZ 65 (serotype d/g) by swallowing 100mg of formalin killed bacteria in capsules for three successive days. After a period, immunization was repeated except that capsules were ingested on seven successive days. Samples of blood, whole and parotid saliva and tears were collected throughout the experiment and assayed for antibodies to OMZ 65 by a fluorescein linked immunoabsorbant assay. Antibody in the IgA class reactive with OMZ 65 was induced in whole and parotid saliva by immunization.